The invention relates to an inertia sensor for vehicle-sensitive activation of a belt retractor blocking mechanism. The invention relates furthermore to a belt retractor comprising a housing and one such inertia sensor as well as to an injection mold for producing a support and an injection mold for producing a sensor lever for such an inertia sensor.
The effect of such an inertia sensor is based on the fact that a mass body which is resting on a support due to its force of gravity, is moved from its resting position when the sensor is accelerated transversely to the force of gravity due to its mass inertia to thereby dislocate the sensor lever so that the contact section of its control pawl engages, for example, the toothing of a control disc of the belt retractor, blocking any movement thereof. For a proper function of the sensor, the sensor needs to be mounted in the vehicle relative to the horizontal in a way that the mass body assumes its resting position, i.e. that the sensor lever is not dislocated when the mass body is not exposed to any further force of inertia than to the force of gravity. The inertia sensor is accommodated in the housing of the belt retractor and the mounting position of the belt retractor may differ from one vehicle to the next. This is why either the fastening arrangement of the sensor in the housing has to be changed or a changed sensor has to be provided for each vehicle type having a different mounting position of the belt retractor. This is in any case undesirable since changing in design involves considerable expense in time and money.
The invention provides an inertia sensor which is configured such that it can simply be produced for various mounting positions of one and the same housing.
The inertia sensor according to the invention comprises a mass body, a support for the mass body, and a sensor lever with a control pawl. The sensor is mounted on the support for swivelling motion about a swivel axis and rests on the mass body. The control pawl has a free end defining a contact section for contact with a control disc of the belt retractor. The support is provided with a first circular cylindrical surface area, the axis of the first circular cylindrical surface area being parallel to the swivel axis and running through the center of gravity of the mass body. An appendix is formed on the first circular cylindrical surface area of the support for mounting the support to the belt retractor.
Since the assigned mounting position of the housing of the belt retractor dictates the orientation of the appendix securing the sensor in the housing, the appendix must be applied to the support under a specific angle so that the sensor can assume a position relative to the horizontal needed for proper functioning of the sensor.
In one advantageous further embodiment of the invention the sensor lever is provided with a second circular cylindrical surface area, the axis of which being parallel to the swivel axis and running through the center of gravity of the mass body, the control pawl being mounted to said second cylindrical surface area. This makes it possible to also apply the control pawl to the sensor lever at various angles so that for the sensor lever the same advantages materialize as for the support.
The invention further provides a belt retractor comprising a housing with a recess, a blocking mechanism with a control disc and an inertia sensor for vehicle-sensitive activation of the blocking mechanism. The inertia sensor comprises a mass body, a support for the mass body, and a sensor lever with a control pawl. The sensor lever is mounted on the support for swivelling motion about a swivel axis and resting on the mass body. The control pawl has a free end defining a contact section for contact with the control disc. The support is provided with a first circular cylindrical surface area. The axis of the first circular cylindrical surface area is parallel to the swivel axis and runs through the center of gravity of the mass body. An appendix is formed on the first circular cylindrical surface area of the support, the appendix having a free end on which a plate is provided. The plate is mounted non-rotatably in the recess. The retractor according to the invention provides for a simple attachment of the sensor to the retractor housing in a predetermined rotational position.
According to another aspect of the invention a belt retractor is provided which comprises a housing with a recess, a blocking mechanism with a control disc, an inertia sensor for vehicle-sensitive activation of the blocking mechanism. The inertia sensor comprises a mass body, a support for the mass body, and a sensor lever with a control pawl. The sensor lever is mounted on the support for swivelling motion about a swivel axis and rests on the mass body. The control pawl has a free end defining a contact section for contact with the control disc. The support is provided with a first circular cylindrical surface area. The axis of the first circular cylindrical surface area is parallel to the swivel axis and runs through the center of gravity of the mass body. An appendix is formed on the first circular cylindrical surface area of the support, the appendix having a longitudinal axis, being of a cylindrical shape with respect to the longitudinal axis and being mounted in the recess so as to be pivotable about the longitudinal axis.
Thus, the invention makes it possible to rotate the sensor about its longitudinal centerline after being installed in the housing so that a further degree of freedom materializes for the mounting position of the housing.
The invention further provides an injection mold for molding of a support according to the invention for supporting a mass body of an inertia sensor for vehicle sensitive activation of a blocking mechanism of a belt retractor. The inertia sensor comprises a sensor lever with a control pawl, the sensor lever being mounted on the support for swivelling motion about a swivel axis and resting on the mass body, the control pawl having a free end defining a contact section for contact with the blocking mechanism. The support is provided with a first circular cylindrical surface area having an axis parallel to the swivel axis and running through the center of gravity of the mass body. An appendix is formed on the first circular cylindrical surface area of the support for mounting the support to the belt retractor. The injection mold according to the invention comprises a first mold part for the support and an insert defining a mold for the appendix. The insert is rotatable about an axis of rotation with respect to the first mold part in such a manner that, by rotating the insert, supports with different angles between the appendix and the first circular cylindrical surface area can be injection molded. The axis of rotation coincides with the swivel axis of the support when molded in the injection mold, the insert adjoining the first mold part along a mold joint surface for forming the first circular cylindrical surface area of the support.
This support finds application in inertia sensors for belt retractors mountable in various mounting positions in the vehicle. Producing a support on which the appendix is molded at a specific angle to the support merely requires the insert to be set by rotation to the mold for the appendix without necessitating a new mold for producing this new component. In addition, considerable savings in time and money materialize from eliminating the need to refit the injection mold.
According to a further aspect, the invention teaches an injection mold for molding of the sensor lever for an inertia sensor according to the present invention for vehicle sensitive activation of a blocking mechanism for belt retractor. The inertia sensor comprises a support for supporting a mass body, the sensor lever having a control pawl with a free end defining a contact section of a contact with the blocking mechanism, the sensor lever being mounted on the support for swivelling motion about a swivel axis and resting on the mass body. The sensor lever is provided with a circular cylindrical surface area having an axis parallel to the swivel axis and running through the center of gravity of the mass body. The control pawl is mounted to the circular cylindrical surface area. The injection mold comprises a first mold part of the sensor lever and an insert defining a mold for the control pawl. The insert is rotatable about an axis of rotation with respect to the first mold part in such a manner that, by rotating the insert, sensor levers with different angles between the appendix and the circular cylindrical surface can be injection molded. The axis of rotating coincides with the swivel axis of the sensor lever when molded in the injection mold. The insert adjoins the first mold part along a mold joint surface for forming the circular cylindrical surface area of the sensor lever.